[37.11] Solar Oscillation Observations with the MDI Line Depth Parameter

The line-depth parameter determined by the Michelson Doppler
Imager (MDI) on the Solar Heliospheric Observatory (SOHO) provides a
measure of magnetic field structures on the Sun. This parameter, along
with the MDI continuum parameter, will be used to estimate the change
in the solar brightness, due to active region effects, at the NaD working
points of the Global Oscillation Low Frequency (GOLF) instrument on
SOHO to allow correction of the GOLF signal. Preliminary comparison of
simultaneous full-disk observations of line-depth and Doppler images
show a weak correlation. We investigate the possible causes for this
correlation. In addition, we use ring-diagram analysis of high-resolution
observations, taken using the MDI line-depth parameter on March 7, 1996,
to study large-scale flows beneath the heliographic south pole.